What is cryotherapy?
The term ‘cryotherapy’ literally means ‘treatment using low temperature’ and refers to the removal of skin lesions by freezing them. Liquid nitrogen is the most common product used.
What is liquid nitrogen?
Liquid nitrogen is the liquid state of gaseous nitrogen, which occupies 78% of the air we breathe. Liquid nitrogen is extremely cold, having a boiling point of minus 196°c. It is necessary to store and transport it in special flasks or vials.
What conditions can be treated with cryotherapy?
A wide variety of superficial benign (non-cancerous) lesions can be treated with cryotherapy, but it is most commonly used to remove actinic keratoses (an area of sun-damaged skin found predominantly on sun-exposed parts of the body), age spots, Cambell De Morgan spots, small cherry angiomas and viral warts, seborrhoeic keratoses, and skin tags.
Does it hurt?
The freezing itself doesn’t hurt. It’s a stinging sensation. For about two hours afterwards you MAY feel sore and some fluid might form under the lesion before the pigmented area of skin falls off – about 36 hours after treatment. You will be given comprehensive advice on how to treat this after the treatment. You should expect to have a sore patch for a few days that will need to be kept clean.
Treatment lasts a couple of minutes per lesion. You may need two or three treatments.
What does the procedure involve?
Liquid nitrogen is applied to the area using a high pressured vial attached to a special pen like device. It allows for a very specific and careful treatment of only the affected area. The frozen skin becomes white and takes one to two minutes to thaw back to normal skin temperature. Isobel may suggest that the process be repeated once the skin has thawed. Immediately after treatment a blister may form or the area will darken. A few days later a crust forms, and this will take one to two weeks to fall off (occasionally a little longer, especially on the legs). Usually, the treated area will eventually look normal, although scarring and discolouration is possible, and rarely ulceration, particularly on the lower legs.
Depending on the nature of the lesion, more than one treatment may be necessary, and this is usually repeated at regular intervals.
How should the treated area be cared for?
Initially you need to keep the area clean with simple soap and water, as a crust forms applying Vaseline to the affected skin helps. If the scabs become wet, they should be patted dry with a soft towel or tissue. It is very important not to pick the scab as this will encourage scarring. A dressing or plaster is not usually necessary but may be advisable if the treated area is likely to be knocked or rubbed by clothing.
What are the side effects of this treatment?
Immediate side effects:
Pain - cryotherapy is usually well-tolerated but can sometimes be painful if a deep freeze has been necessary. This discomfort can occur both at the time of treatment and for a variable time thereafter. Painkillers (such as paracetamol) taken for the first 24 hours may relieve the discomfort; also taking a painkiller an hour or so prior to the anticipated treatment may reduce the discomfort.
Swelling and redness - this is a normal immediate response to freezing the skin and usually settles after two to three days. For a short while the treated area may ooze a little watery fluid. Cryotherapy close to the eyes may induce prominent puffiness of the lower eyelids which settles within days.
Blistering - this is also a common consequence of cryotherapy and blisters settle after a few days as the scab forms. Some people blister more easily than others and the development of blisters does not necessarily mean that the skin has been frozen too much.
Infection - uncommonly, infection can occur, resulting in increased pain and the formation of pus: this may require topical antiseptic or antibiotic therapy .
Subsequent side effects:
Scarring - rarely, a scar will form, especially if a deep freeze has been necessary
Hypertropic/Keloid scarring – very rarely a raised scar can form following treatment with cryotherapy which appears as a rounded, hard growth on the skin. These are harmless lesions, more common in dark skinned individuals compared to Caucasians.
Pigmentation changes - the skin at and around the treatment site may lighten or darken in colour, especially in dark-skinned people. This usually improves with time but may be permanent.
Numbness - if a superficial nerve is frozen, it may result in numbness of the area of skin supplied by that nerve. Normal feeling usually returns within a matter of months.
Treatment may not be effective, or the condition may recur.
Where can I get more information about cryotherapy?